Japanese auto maker Nissan Motor executive Hideaki Waqtanabe demonstrates how to use an electricity supply for the Nissan Leaf to a "smart house" near Nissan's headquarters in Yokohama, suburban Tokyo on August 2, 2011.

PHOTO: Yoshikazu Tsuno, AFP/Getty Images

2012 Nissan Leaf.

PHOTO: Nissan, handout

An employee of Japan's auto maker Nissan Motor demonstrates how to use an electricity supply for the Nissan Leaf to a "smart house" near Nissan's headquarters (seen behind) in Yokohama, suburban Tokyo on August 2, 2011.